当前线程与 Dispatcher 无关.触发渲染时使用 InvokeAsync() 将执行切换到 Dispatcher [英] The current thread is not associated with the Dispatcher. Use InvokeAsync() to switch execution to the Dispatcher when triggering rendering

问题描述

我正在使用 Dotnet Core Blazor 并且在删除事件后使用 EventCallBack 绑定父网格时出现以下错误.下面是使用子组件的代码

I am working on Dotnet Core Blazor and getting below error while using EventCallBack to bind the parent grid after delete events. Below the code for using Child component

<tbody>
      @foreach (var employee in Employees)
       {
          <BlazorAppDemo.Pages.Controls.EmployeeList Employee="employee"
                                                           ShowFooter="ShowFooter"
                                                           OnEmployeeSelectionChange="onEmployeeSelectionChanged"
                                                           btnDeleteClick="OnEmployeeDeleted" >

            </BlazorAppDemo.Pages.Controls.EmployeeList>
        }
    </tbody> 

EmployeeList 子组件在下面

EmployeeList child component is below

<tr>
@*<td>@Employee.EmployeeId</td>*@
<td><input type="checkbox" @onchange="CheckBoxChanged" /></td>
<td>@Employee.Department.DepartmentName</td>
<td>@Employee.FirstName</td>  
<td>@Employee.DateOfBirth.ToShortDateString()</td>
<td><img class="card-img-top img-thumb" style="width:50px;height:50px" src="@Employee.PhotoPath" /></td>
@if (ShowFooter)
{
    <AuthorizeView Roles="Admin" Policy="OldEmployeeBefore2020">
        <Authorized>
            <td>
                <a href="@($"employeedetails/{Employee.EmployeeId}")" class="btn btn-primary m-1">View</a>
                <a href="@($"employeeEdit/{Employee.EmployeeId}")" class="btn btn-primary m-1">Edit</a>
                @*<a href="#" class="btn btn-danger m-1">Delete</a>*@
                <button class="btn btn-danger m-1" @onclick="btnDelete_Click">
                </button>
            </td>
        </Authorized>
    </AuthorizeView> 
}

删除按钮事件:

 [Parameter]
    public EventCallback<int> btnDeleteClick { get; set; }

 protected async Task btnDelete_Click()
    {
        var response = await EmployeeService.Delete(Employee.EmployeeId).ConfigureAwait(false);

        if (string.IsNullOrEmpty(response.ErrorMessage))
        {               
            await btnDeleteClick.InvokeAsync(Employee.EmployeeId);               
            //NavigationManager.NavigateTo("employee");
        }
    }

父页面已订阅删除事件:

Parent page has subscribed the delete event:

 protected async Task OnEmployeeDeleted(int id)
    {
        var response = await EmployeeService.GetEmployees().ConfigureAwait(false);
        if (response.Result != null)
        {  
            Employees = response.Result.Result; 
        }
        else
        {
            PageMessage = response.ErrorMessage;
        }
    }

推荐答案

您应该删除 .ConfigureAwait(false)(据我所知是 2 倍).

You should remove the .ConfigureAwait(false) (2x as far as I coud see).

当您在 Blazor 中正确使用 async/await 时，您几乎不需要它.

When you use async/await correctly in Blazor you should almost never need it.

当您使用它时，您要求在不同的线程上运行该事件的其余部分.大多数情况下是错误的线程.

When you do use it you are asking for the remainder of the event to be run on a different thread. The wrong thread in most cases.

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